A series of interrelated experiments are designed to explore the chemical and physical interactions of the photoreceptor cells and the pigment epithelium in normal rats and in rats suffering from hereditary retinal degeneration (RCS rats). Pigment epithelium cells will be grown in tissue culture, and the phagocytosis of polystyrene beads and rod outer segments by cells from normal and dystrophic rats will be studied. Experiments are designed to localize the site of expression of the genetic defect to either the photoreceptor cell outer segments or to the pigment epithelium. Further experiments will explore the biochemical characteristics of the plasma membranes of the pigment epithelium and the photoreceptor cells with a view to defining the molecular nature of the genetic defect in RCS rats. These studies will utilize the techniques of protein labeling with radioiodine, protein biosynthesis and ferritin-lectin binding studies. The mechanism of vitamin A uptake by the pigment epithelium and the role of specific carriers in this process will be studied. Finally, the synthesis and chemistry of mucopolysaccharides synthesized by normal and dystrophic rat pigment epithelium will be investigated. The results obtained from these experiments will hopefully better our understanding of inherited retinal disorders which involve the photoreceptors and the pigment epithelium.